rails simple_form using virtual attributes - ruby-on-rails-4

Question

I am trying to incorporate Simple_forms into my app using a virtual attributes. I am following http://railscasts.com/episodes/102-auto-complete-association-revised to get autocomplete to work as well. Simple_form works when i do not use a virtual attribute but when I do use the virtual attribute I get the error "Association :head_coach_name not found".
My Team Model is:
class Team < ActiveRecord::Base
attr_accessor :head_coach_name
belongs_to :user
validates :team_name, presence: true
belongs_to :head_coach, class_name: "User", :foreign_key => "head_coach_id"
def head_coach_name
user.try(:name)
end
def head_coach_name=(name)
self.user = User.find_by_name(name) if name.present?
end
end
My User model is:
class User < ActiveRecord::Base
has_many :teams, :class_name => "::Team", dependent: :destroy
end
My View:
<%= simple_form_for #team, html: {class: 'form-horizontal' }, url: teams_path, method: 'post' do |f| %>
<%= f.error_notification %>
<%= f.hidden_field :user_id %>
<div class="col-md-6">
<div class="row">
<div class="col-md-12">
<%= f.input :team_name, class: "form-control" %>
<%= f.input :year, collection: Date.today.year-90..Date.today.year %>
<%= f.input :season, as: :select, collection:
['Fall',
'Winter',
'Spring',
'Summer'] %>
<%= f.input :season_type, as: :select, collection:
['Outdoor',
'Indoor',
'Tournament'] %>
<%= f.input :awards %>
</div>
</div>
</div>
<div class="col-md-6">
<div class="row">
<div class="col-md-12">
<%= f.input :club %>
<%= f.input :division %>
<%= f.association :head_coach_name %>
<%= f.input :assistant_coach_id %>
<%= f.input :assistant_coach_two_id %>
</div>
</div>
</div>
<%= f.button :submit, label: "Add team", class: "btn btn-large btn-primary col-md-3 pull-right" %>
<% end %>
Everything works as long as i don't have the virtual association in there. I could put :head_coach and it would work with a drop down list but I want to use the autocomplete feature like in the railscast video. Also in rails console i can run these commands to show the virtual attribute works:
2.1.2 :003 > team.head_coach_name
User Load (0.6ms) SELECT `users`.* FROM `users` WHERE `users`.`id` = 100 LIMIT 1
=> "Miss Daisha Shanahan"
Any ideas on how I can get the virtual attribute to work correctly with simple_forms?

Answer 1

You are referencing an association that doesn't exist with f.association :head_coach_name. Try this instead:
f.association :head_coach, label_method: :head_coach_name
You have a few other oddities in your code, including your head_coach_name definition, which should rely on head_coach instead of user. Same concern for the head_coach_name= method.
Example. You have:
def head_coach_name
user.try(:name)
end
Seems like you should have:
def head_coach_name
head_coach.try(:name)
end